“If one advances confidently in the direction of his dreams, he        will meet with a success  unexpected in common hour...
DR.M.RAVICHANDRA,M.SASST. PROFESSOR OF SURGERY      RIMS ,SRIKAKULAM
Strong and Weak Acids and Bases A strong acid ..rapidly dissociates and releases  large amounts of H+ in solution….HCl W...
   Volatile acids:     Can leave solution and enter the atmosphere.     H2C03 (carbonic acid).     Pco2   is most impo...
   Fixed Acids:     Acids that do not leave solution.     Sulfuric and phosphoric acids.(H2SO4&H3PO4)     Catabolism o...
   Organic Acids:     Byproducts of aerobic metabolism, during anaerobic      metabolism and during starvation, diabetes...
Normal Hydrogen Ion Concentration and pH of Body  Fluids the blood H+ concentration is normally maintained  within tight ...
pH = pK + log HCO3              CO2
DEFENCE MECHANISMSAGAINST pHCHANGES
1.CHEMICAL BUFFER SYSTEMS
There are three primary systems that  regulate the H+ concentration(1)   the chemical acid-base buffer systems of      the...
   a buffer system is a combination of two    compounds that minimizes pH changes when    acid or base is added to a solu...
   Chemical buffer system     Combination   of weak acid and weak base     Binds to H+ as H+ concentration rises     R...
   Accomplished by converting:     Strong acid  Weak acid     Strong base  Weak base
 bicarbonate/carbonic       acid    major plasma buffer phosphate:     H2PO4- / HPO42-    major urine buffer ammonium...
BICARBONATE BUFFER SYSTEM Carbonic acid (H2CO3)     Weak    acid   Bicarbonate ion (HCO3-)     Weak    base   CO2 + H...
NaOH + H2CO3    H2O + Na HCO3HCl + Na HCO3   NaCl + H2CO3
BICACARBONATE BUFFER
Bing via Image*
 Bing via Image*
   pK 6.1   the concentrations of CO2 and HCO3 not great.   the most powerful extracellular buffer in the body   the t...
PHOSPHATE BUFFER SYSTEM Dihydrogen phosphate ion (H2PO4-)     Weak   acid   Monohydrogen phosphate ion (HPO42-)     We...
The main elements of the phosphate buffer system are H2PO4- and HPO4NaOH + NaH2PO4           H2O+ Na2HPO4HCl + Na2HPO4    ...
   pK 6.8   8 % of the concentration of the bicarbonate    buffer   the total buffering power less than that of the    ...
   the phosphate buffer is important in the tubular    fluids of the kidney for two reasons(1) phosphate concentrated in ...
 Bing via Image*
PROTEIN BUFFER SYSTEM Proteins are more concentrated than bicarbonate  and phosphate buffers   Accounts for ~75% of all ...
   except for the red blood cells, the slowness    with which H+ and HCO3 move through the cell    membranes often delays...
The buffer system buffers each other by shifting hydrogen from buffer to other
   Exhalation of carbon dioxide   Powerful, but only works with volatile acids   Doesn’t affect fixed acids like lactic...
   the overall buffering power of the respiratory    system is one to two times as great as the buffering    power of all...
 Bing via Image*
 Bing via Image*
   Alkalosis    →↑urinary HCO3- (base)   Acidosis    →↓urinary HCO3-       new HCO3- production
   pH< 7.35 acidosis   pH > 7.45 alkalosis
   A CONDITION WHERE THE PCO2 IS ABOVE THE    NORMAL RANGE        MORE THAN 5.6 kilopascals        (or) more than 42mmo...
*Image via Bing 
*Image via Bing 
*Image via Bing 
*Image via Bing 
*Image via Bing 
compensatory mechanisms in respiratory acidosis       compensatory mechanisms in respiratory acidosis*Image via Bing 
   Inadequate ventilation of anaesthetized    patient   When the effects of muscle relaxants have    not worn off or bee...
   A CONDITION WHERE THE ARTERIAL PCO2 IS    BELOW THE NORMAL RANGE        LESS THAN 31 MM OF HG        (OR) LESS THAN ...
*Image via Bing 
   Excessive pulmonary ventilation during    ANAESTHAESIA (Hyperventilation)   High altitudes   Hyperpyrexia   Hypotha...
   A condition where there is a deficit of base    or excess of acid other than carbonic    acid(H2CO3)
Ulcerative colitisGastro colic fistulaHigh intestinal fistula Prolonged  intestinal aspiration
*Image via Bing 
*Image via Bing 
*Image via Bing 
   This is a calculated estimation of the    undetermined or unmeasured anions in the    blood   This is some times used...
*Image via Bing 
*Image via Bing 
*Image via Bing 
   KETOACIDOSIS   LACTIC ACIDOSIS   SALICYLATES POISONING   SPIRITS –ETHANOL & METHANOL   ALDEHYDES   RENAL FAILURE
   DIARRHOEA   RENAL TUBULAR ACIDOSIS   URETEROSIGMOIDOSTOMY   TOTAL PARENTARAL NUTRITION   ACETAZOLAMIDE   INTESTIN...
   Increased ventilation   Renal excretion of hydrogen ions if possible   K+ exchanges with excess H+ in ECF   ( H+ in...
   A CONDITION WHERE THERE IS BASE EXCESS    OR DEFICIT OF ANY ACID OTHER THAN    CARBONIC ACID
Cortisone excessCushings syndrome
CHEYNE STOKES RESP                       TETANY*Image via Bing 
*Image via Bing 
*Image via Bing 
   RESPIRATORY- RETENTION OF    CARBONDIOXIDE BY THE LUNGS   RENAL – EXCRETION OF BICARBONATE BY THE    KIDNEYS
Changes in Arteial Concentrations     of H + , HCO 3 - & CO 2 in Acid-Base Disorders Primary              HCO 3          C...
 Respiratory Acidosis ; ↑PCO2 & [H+] Respiratory Alkalosis ; ↓PCO2 & [H+] Metabolic Acidosis    ; compensatory reflex h...
 Metabolic Alkalosis    ; compensatory reflex hypoventilation ⇒ ↑PCO2  1. Diuretics; ↑distal tubule flow             ⇒↑Na...
Summary of Acid-Base Disturbances               Uncompensated                 Compensated              pH    [HCO 3 - ]   ...
HAVE A NICE DAYHAVE A NICE DAY    *Image by 8771253@N06 via Flickr 
Acid base balance
Acid base balance
Acid base balance
Acid base balance
Acid base balance
Acid base balance
Acid base balance
Acid base balance
Acid base balance
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Acid base balance

  1. 1. “If one advances confidently in the direction of his dreams, he will meet with a success unexpected in common hours --Henry David Thoreau "Shoot for the moon. Even if you miss it, you will land among the stars….!" - Les Brown 
  2. 2. DR.M.RAVICHANDRA,M.SASST. PROFESSOR OF SURGERY RIMS ,SRIKAKULAM
  3. 3. Strong and Weak Acids and Bases A strong acid ..rapidly dissociates and releases large amounts of H+ in solution….HCl Weak acids ..less tendency to dissociate their ions … is H2CO3 A strong base … reacts rapidly and strongly with H+ and quickly removes these from a solution… OH- A typical weak base is HCO3- Most of the acids and bases in the extracellular fluid that involved in normal acid-base regulation are weak acids and bases
  4. 4.  Volatile acids:  Can leave solution and enter the atmosphere.  H2C03 (carbonic acid).  Pco2 is most important factor in pH of body tissues.  Pco2 is a measurement of tension or partial pressure of carbon dioxide in the blood. The normal arterial pCO2 is 4.1- 5.6 k Pa (31- 42 mmHg)
  5. 5.  Fixed Acids:  Acids that do not leave solution.  Sulfuric and phosphoric acids.(H2SO4&H3PO4)  Catabolism of amino acids, nucleic acids, and phospholipids.
  6. 6.  Organic Acids:  Byproducts of aerobic metabolism, during anaerobic metabolism and during starvation, diabetes.  LACTIC ACID, KETONES ,PYRUVIC ACID
  7. 7. Normal Hydrogen Ion Concentration and pH of Body Fluids the blood H+ concentration is normally maintained within tight limits around a normal value of about 0.00004 mEq/L (40 nEq/L)Ph= log 1/H= -log [H]Ph=7.4
  8. 8. pH = pK + log HCO3 CO2
  9. 9. DEFENCE MECHANISMSAGAINST pHCHANGES
  10. 10. 1.CHEMICAL BUFFER SYSTEMS
  11. 11. There are three primary systems that regulate the H+ concentration(1) the chemical acid-base buffer systems of the body fluids(2) the respiratory center(3) the kidneys
  12. 12.  a buffer system is a combination of two compounds that minimizes pH changes when acid or base is added to a solution A pair of substance is involved: one substance yield H+ ion when PH is increased the other binds with H+ ion when pH is decreased.
  13. 13.  Chemical buffer system  Combination of weak acid and weak base  Binds to H+ as H+ concentration rises  Releases H+ as H+ concentration falls  Can restore normal pH almost immediately  Three major chemical buffer systems  Bicarbonate system  Phosphate system  Protein system
  14. 14.  Accomplished by converting:  Strong acid  Weak acid  Strong base  Weak base
  15. 15.  bicarbonate/carbonic acid  major plasma buffer phosphate: H2PO4- / HPO42-  major urine buffer ammonium: NH3 / NH4+  also used to buffer the urine proteins: important in ICF Hb: is the main buffer against CO2 changes
  16. 16. BICARBONATE BUFFER SYSTEM Carbonic acid (H2CO3)  Weak acid Bicarbonate ion (HCO3-)  Weak base CO2 + H20  H2CO3  H+ + HCO3- Works along with respiratory and urinary system  These systems remove CO2 or HCO3- THE RATIO OF BICARBONATE TO CARBONIC ACID IS NORMALLY 20:1 Alterations in the ratio alters Ph irrespective of absolute concetrations
  17. 17. NaOH + H2CO3 H2O + Na HCO3HCl + Na HCO3 NaCl + H2CO3
  18. 18. BICACARBONATE BUFFER
  19. 19. Bing via Image*
  20. 20.  Bing via Image*
  21. 21.  pK 6.1 the concentrations of CO2 and HCO3 not great. the most powerful extracellular buffer in the body the two elements of the buffer system are regulated by the kidneys and the lungs
  22. 22. PHOSPHATE BUFFER SYSTEM Dihydrogen phosphate ion (H2PO4-)  Weak acid Monohydrogen phosphate ion (HPO42-)  Weak base H2PO4-  H+ + HPO42- More important in buffering kidney filtrate than in tissue
  23. 23. The main elements of the phosphate buffer system are H2PO4- and HPO4NaOH + NaH2PO4 H2O+ Na2HPO4HCl + Na2HPO4 NaCl + NaH2PO4
  24. 24.  pK 6.8 8 % of the concentration of the bicarbonate buffer the total buffering power less than that of the bicarbonate buffering system.
  25. 25.  the phosphate buffer is important in the tubular fluids of the kidney for two reasons(1) phosphate concentrated in the tubules(2) the tubular fluid has lower pH than the extracellular fluid does - bringing the operating range of the buffer closer to the pK (6.8) of the system important in buffering intracellular fluid because the concentration of phosphate in this fluid is many times that in the extracellular fluid
  26. 26.  Bing via Image*
  27. 27. PROTEIN BUFFER SYSTEM Proteins are more concentrated than bicarbonate and phosphate buffers Accounts for ~75% of all chemical buffering of body fluids Buffering ability due to certain functional groups of amino acid residues
  28. 28.  except for the red blood cells, the slowness with which H+ and HCO3 move through the cell membranes often delays the maximum ability of the intracellular proteins to buffer extracellular acid-base abnormalities. the pKs of many of these protein systems close to 7.4.
  29. 29. The buffer system buffers each other by shifting hydrogen from buffer to other
  30. 30.  Exhalation of carbon dioxide Powerful, but only works with volatile acids Doesn’t affect fixed acids like lactic acid CO2 + H20 ↔ H2CO3 ↔ H+ + HCO3- Body pH can be adjusted by changing rate and depth of breathing
  31. 31.  the overall buffering power of the respiratory system is one to two times as great as the buffering power of all other chemical buffers in the ECF combined
  32. 32.  Bing via Image*
  33. 33.  Bing via Image*
  34. 34.  Alkalosis →↑urinary HCO3- (base) Acidosis →↓urinary HCO3- new HCO3- production
  35. 35.  pH< 7.35 acidosis pH > 7.45 alkalosis
  36. 36.  A CONDITION WHERE THE PCO2 IS ABOVE THE NORMAL RANGE  MORE THAN 5.6 kilopascals  (or) more than 42mmof hg
  37. 37. *Image via Bing 
  38. 38. *Image via Bing 
  39. 39. *Image via Bing 
  40. 40. *Image via Bing 
  41. 41. *Image via Bing 
  42. 42. compensatory mechanisms in respiratory acidosis compensatory mechanisms in respiratory acidosis*Image via Bing 
  43. 43.  Inadequate ventilation of anaesthetized patient When the effects of muscle relaxants have not worn off or been fully reversed at the end of anaesthesia Risk increases when the patient has pre existing pulmonary disease like ch. Bronchitis or emphysema Thoracic & upper abdominal incisions
  44. 44.  A CONDITION WHERE THE ARTERIAL PCO2 IS BELOW THE NORMAL RANGE  LESS THAN 31 MM OF HG  (OR) LESS THAN 5.6 KILO PASCALS
  45. 45. *Image via Bing 
  46. 46.  Excessive pulmonary ventilation during ANAESTHAESIA (Hyperventilation) High altitudes Hyperpyrexia Hypothalamic lesions Hysteria
  47. 47.  A condition where there is a deficit of base or excess of acid other than carbonic acid(H2CO3)
  48. 48. Ulcerative colitisGastro colic fistulaHigh intestinal fistula Prolonged  intestinal aspiration
  49. 49. *Image via Bing 
  50. 50. *Image via Bing 
  51. 51. *Image via Bing 
  52. 52.  This is a calculated estimation of the undetermined or unmeasured anions in the blood This is some times used to establish the cause of metabolic acidosis ANIONGAP= (Na) _ (HCO3+Cl) NORMAL ANION GAP IS 10-16 mmol / L
  53. 53. *Image via Bing 
  54. 54. *Image via Bing 
  55. 55. *Image via Bing 
  56. 56.  KETOACIDOSIS LACTIC ACIDOSIS SALICYLATES POISONING SPIRITS –ETHANOL & METHANOL ALDEHYDES RENAL FAILURE
  57. 57.  DIARRHOEA RENAL TUBULAR ACIDOSIS URETEROSIGMOIDOSTOMY TOTAL PARENTARAL NUTRITION ACETAZOLAMIDE INTESTINAL OBSTRUCTION INTESTINAL FISTULA
  58. 58.  Increased ventilation Renal excretion of hydrogen ions if possible K+ exchanges with excess H+ in ECF ( H+ into cells, K+ out of cells)
  59. 59.  A CONDITION WHERE THERE IS BASE EXCESS OR DEFICIT OF ANY ACID OTHER THAN CARBONIC ACID
  60. 60. Cortisone excessCushings syndrome
  61. 61. CHEYNE STOKES RESP TETANY*Image via Bing 
  62. 62. *Image via Bing 
  63. 63. *Image via Bing 
  64. 64.  RESPIRATORY- RETENTION OF CARBONDIOXIDE BY THE LUNGS RENAL – EXCRETION OF BICARBONATE BY THE KIDNEYS
  65. 65. Changes in Arteial Concentrations of H + , HCO 3 - & CO 2 in Acid-Base Disorders Primary HCO 3 Cause of HCO3- Cause of CO2 H + CO 2 Disorder - Change ChangeRespiratory Acidosis ↑ ↑ ↑ Renal Primary Compensation AbnormalityRespiratory Alkalosis ↓ ↓ ↓MetabolicAcidosis ↑ ↓ ↓ Reflex Primary Ventilatory AbnormalityMetabolic CompensationsAlkalosis ↓ ↑ ↑
  66. 66.  Respiratory Acidosis ; ↑PCO2 & [H+] Respiratory Alkalosis ; ↓PCO2 & [H+] Metabolic Acidosis ; compensatory reflex hyperventilation ⇒ ↓PCO2 1. Tubular acidosis; ↓HCO3- reabsorption & H+ secretion 2. Diarrhea & Vomiting(intestinal); ↓HCO3- 3. Diabetes Mellitus; ↑acetoacetic acid (ketone body) 4. Ingestion of acids; aspirin, methyl alcohol 5. Chronic renal failure; ↓acid excretion 6. Hypoxia (severe exercise); ↑lactic acid
  67. 67.  Metabolic Alkalosis ; compensatory reflex hypoventilation ⇒ ↑PCO2 1. Diuretics; ↑distal tubule flow ⇒↑Na+ reabsorption & H+ secretion 2. Excess Aldosterone; ↑H+ secretion 3. Vomiting; ↓H+ (upper gastric content) 4. Ingestion of alkaline drugs; sodium bicarbonate
  68. 68. Summary of Acid-Base Disturbances Uncompensated Compensated pH [HCO 3 - ] P CO2 pH [HCO 3 - ] P CO2 24 40 Normal 7.4 mEq/L mmHgRespiratory Acidosis ↓ - ↑ ↓ ↑ ↑Respiratory Alkalosis ↑ - ↓ ↑ ↓ ↓MetabolicAcidosis ↓ ↓↓ - ↓ ↓↓ ↓MetabolicAlkalosis ↑ ↑↑ - ↑ ↑↑ ↑
  69. 69. HAVE A NICE DAYHAVE A NICE DAY *Image by 8771253@N06 via Flickr 

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